Article having predetermined surface shape and method for preparing the same

ABSTRACT

An article having a predetermined surface configuration, such as an optical element having fine irregularities in the surface which has high heat resistance, small heat shrinkage at the time of molding a film and high dimensional stability, and a production process therefor. The article having a predetermined surface configuration is produced by setting a composition comprising a compound which contains a dimethylsiloxane skeleton having at least three recurring units and at least one polymerizable organic group in the molecule between and in contact with the surface of a substrate and the molding surface of a mold in the form of a film, applying at least one of heat and ultraviolet radiation to the composition, removing the mold, and heating as required to form a film having a surface configuration which is the inversion of the surface configuration of the mold on the surface of the substrate.

FIELD OF THE INVENTION

The present invention relates to an article having a predeterminedsurface configuration and to a production process therefor. Morespecifically, it relates to an article having a predetermined surfaceconfiguration typified by optical elements such as reflection typediffraction gratings, transmission type diffraction gratings, lensarrays and Fresnel lenses and to a production process therefor.

DESCRIPTION OF THE PRIOR ART

Optical elements such as diffraction gratings and microlens arrays musthave predetermined fine irregularities in the surface.

As means of forming such irregularities in the surface, there is known amethod in which an ultraviolet curable resin monomer is uniformly spreadover a substrate and exposed to ultraviolet radiation while it iscontacted to a mold having irregularities (JP-A 63-49702) (the term“JP-A” as used herein means an “unexamined published Japanese patentapplication”).

Also JP-A 62-102445 and JP-A 6-242303 disclose a production process inwhich irregularities are formed in the surface of a substrate byapplying a solution containing silicon alkoxide to a glass substrate,pressing a mold having irregularities against the coating film andheating.

However, in the technology of the above JP-A 63-49702, the ultravioletcurable monomer has large shrinkage in the photopolymerization step andtherefore may not achieve high accuracy required for an optical element.The monomer also has a problem with heat resistance.

In contrast to this, an optical element obtained by thermally curingsilicon alkoxide has excellent heat resistance but it has largeshrinkage in the hydrolysis/polycondensation reaction step and thereforemay not achieve high accuracy required for an optical element.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an article having apredetermined surface configuration, such as an optical element havingfine irregularities in the surface, which has high heat resistance,small thermal shrinkage at the time of molding a film and highdimensional accuracy, by solving the above problems existent in theprior art.

It is another object of the present invention to provide an industriallyadvantageous process for producing the above article of the presentinvention.

Other objects and advantages of the present invention will becomeapparent from the following description.

According to the present invention, firstly, the above objects andadvantages of the present invention are attained by a process forproducing an article having a predetermined surface configuration,comprising the steps of:

setting a composition comprising a compound which contains adimethylsiloxane skeleton having at least three recurring units and atleast one polymerizable organic group in the molecule between and incontact with the surface of a substrate and the molding surface of amold in the form of a film;

applying at least one of heat and ultraviolet radiation to thecomposition set in the form of a film;

removing the mold and, as required, heating the film; and

forming the article in which the surface of the substrate is coveredwith a film having a surface configuration which is the inversion of thesurface configuration of the mold.

According to the present invention, secondly, the above objects andadvantages of the present invention are attained by an article having apredetermined surface configuration, comprising a substrate and anorganopolysiloxane film having a predetermined uneven surface and amaximum thickness of 1 μm to 1 mm formed on the surface of thesubstrate, wherein the organopolysiloxane film contains 10 to 50 wt % ofa methyl group, 1 to 30 wt % of a polymerized segment of a polymerizableorganic group and 45 to 89 wt % of a Si—O bonding segment, the total ofthe methyl group and the polymerized segment of the polymerizableorganic group being 11 to 55 wt %.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be described in detail hereinunder. Adescription is first given of the production process of the presentinvention.

The composition used in the process of the present invention comprises acompound having linear and branched dimethylsiloxane skeletons havingthree or more recurring units. The dimethylsiloxane skeletons contributeto the heat resistance and low shrinkage of the obtained film. When thenumber of recurring units represented by—((CH₃)₂Si—O)— is too small, theviscosity of a liquid composition becomes too low and when the number ofthe recurring units is too large, the viscosity of the liquidcomposition becomes too high. In any case, coating and other works andhandling become difficult. The number of the recurring units ispreferably 3 to 200, more preferably 3 to 100, the most preferably 3 to50. The compound also has at least one polymerizable organic group inthe molecule. Photopolymerization (or thermopolymerization) is caused bythe addition polymerization of a radical or cation formed by the optical(or thermal) decomposition of an initiator to the polymerizable organicgroup. Therefore, shrinkage is smaller than in a dehydrationcondensation reaction and a chemically bonded uniform organic-inorganiccomposite film can be formed instantaneously. Consequently, an organicgroup which is polymerized by light or heat is used as the polymerizableorganic group. Examples of the photopolymerizable organic group includeacryloxy group, methacryloxy group, vinyl group, epoxy group and organicgroups containing these. Examples of the thermopolymerizable organicgroup include vinyl group, epoxy group and organic groups containingthese. At least two of these groups are preferably contained in themolecule of the above compound when the polymerizable organic group isan acryloxy group, methacryloxy group or vinyl group. Organic groupscontaining an acryloxy group include acryloxy group-substituted alkylgroups such as acryloxypropyl group and acryloxy group-substitutedhydroxyalkyl groups. Organic groups containing a methacryloxy groupinclude methacryloxy group-substituted alkyl groups, methacryloxyethoxygroup and methacryloxypolyethylene group. Organic groups containing avinyl group include vinylbenzyloxy group, N-vinylformamide group andvinyloxy group. Organic groups containing an epoxy group include epoxygroup-substituted propoxy groups, epoxycyclohexylethyl group andepoxyethylphenyl group. Since heat resistance and humidity resistancelower when too many polymerizable organic groups are contained in themolecule, the number of polymerizable organic groups in the molecule ispreferably 50 or less.

The above compound is, for example, a dimethylpolysiloxane having apolymerizable organic group at both terminals represented by thefollowing formula (1):

wherein R¹ and R² are each independently a vinyl group or a group havingan acryloxy group, methacryloxy group or epoxy group, and n is aninteger of 3 to 200, or a dimethylpolysiloxane having a trimethylsilylgroup at both terminals and two or more polymerizable organic groupsrepresented by the following formula (2):

wherein R³ is a vinyl group or a group having an acryloxy group,methacryloxy group or epoxy group, m is an integer of 2 to 200, n is aninteger of 1 to 50 when R³ is an epoxy group and an integer of 2 to 50when R³ is another group, with the proviso that m+n is 3 to 200.

Illustrative examples of the compound include(acryloxypropyl)methylsiloxane-dimethylsiloxane copolymer,(methacryloxypropyl)methylsiloxane-dimethylsiloxane copolymer,vinylmethylsiloxane-dimethylsiloxane copolymer and(epoxycyclohexylethyl)methylsiloxane-dimethylsiloxane copolymer.

Out of these compounds, a polydimethylpolysiloxane having a linearacryloxypropyl group at both terminals (the number of recurring unitsrepresented by (—((CH₃)₂Si—O)— is 3 to 50) and apolydimethylpolysiloxane having a linear methacryloxypropyl group atboth terminals (the number of recurring units represented by(—((CH₃)₂Si—O)— is 3 to 50) are preferred. Out of these, apolydimethylpolysiloxane having a linear acryloxypropyl group at bothterminals (the number of the recurring units of this is 10 to 25) and apolydimethylpolysiloxane having a linear methacryloxypropyl group atboth terminals (the number of the recurring units of this is 10 to 25)are more preferred. When adhesion between the film and a quartzsubstrate must be further improved, an epoxysiloxane is preferred and abranched epoxysiloxane is particularly preferred.

The above liquid composition used in the present invention comprises aphotopolymerization initiator when the polymerizable organic group ofthe compound is photopolymerizable. Examples of the radicalphotopolymerization initiator include[2-hydroxy-2-methyl-1-phenylpropan-1-one],[1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one],[4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl ketone)],[2,2-dimethoxy-1,2-diphenylethane-1-one],[1-hydroxy-cyclohexyl-phenyl-ketone], [2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropane-1-one],[bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide] and[2-benzyl-2-dimethylamino-1-1-(4-morpholinophenyl)-butanone-1]. Examplesof the cationic photopolymerization initiator includephenyl-[m-(2-hydroxytetradecyclo)phenyl]iodonium hexafluoroantimonateand diphenyliodonium tetrakis(pentafluorophenyl)borate. The amount ofthe photopolymerization initiator is preferably 0.1 to 5 wt % based onthe total weight of the liquid composition.

The above liquid composition is set between and in contact with thesurface of the substrate and the surface of the mold in the form of afilm, at least one of heat and ultraviolet radiation is applied to thecomposition set in the form of a film, the mold is removed, and thecomposition is heated as required to form an article having apredetermined surface configuration, such as an optical element in whichthe surface of the substrate is covered with a film having a surfaceconfiguration which is the inversion of the surface configuration of themold. The following two processes are typically used to form thearticle.

In the first process (to be referred to as “mold casting process”hereinafter), the liquid composition is poured over a mold, degasifiedand assembled with a substrate, at least one of heat and ultravioletradiation is applied to the assembly, the mold is removed, and themolded product is heated as required. That is, the mold havingpredetermined fine irregularities in the molding surface is kepthorizontal with the molding surface facing up, and the liquidcomposition having a viscosity of 1 to 200 cSt is poured over the moldto fill depressions in the mold. In place of pouring, the mold may beimmersed in a bath of the liquid composition, or the liquid compositionmay be applied to the molding surface of the mold with a brush. In thisstate, the liquid composition is maintained at room temperature to 100°C. under a reduced pressure of 2 to 5 Pa for 5 to 10 minutes in such amanner that air should not be contained in the liquid composition on themold in order to remove bubbles or dissolved oxygen contained in theliquid.

Then, the substrate is contacted to the liquid on the mold in such amanner that a gap should not be formed between the liquid compositionand the surface of the substrate in order to set the liquid compositionbetween and in contact with the surface of the substrate and the moldingsurface of the mold in the form of a film, and the liquid composition ismaintained at 20 to 100° C. for 1 to 30 minutes while it is exposed toultraviolet radiation or heated at 140 to 250° C. for 10 to 120 minutesin that state to be polymerized and cured. In the case of exposure toultraviolet radiation, at least one of the substrate and the mold ismade from a material which transmits ultraviolet radiation.Subsequently, by stripping off and removing the mold, a film of a curedpolydimethylsiloxane having irregularities in the surface which are theinversion of irregularities in the surface of the mold is formed in sucha state that it is adhered to the surface of the substrate.

This film is finally heated at 180 to 350° C. under normal pressure or areduced pressure of 2 to 5 Pa for 15 to 250 minutes as required tovaporize the residual initiator and unpolymerized product contained inthe polysiloxane film with the result that the film is slightly shrunkenin volume in a thickness direction to become a compact film. Thus, anarticle such as an optical element covered with a film having a surfaceconfiguration which is the inversion of the surface configuration of themold is obtained.

In the second molding process (to be referred to as “substrate castingprocess” hereinafter), the liquid composition is directly poured overthe surface of the substrate and degasified, the mold is pressed againstthe film on the surface of the substrate, the film is exposed toultraviolet radiation or heated in this state, the surface configurationof the mold is transferred to the surface of the film, the mold isremoved, and the film is finally heated as required. That is, thesurface to be covered of the substrate is maintained horizontal and theliquid composition having a viscosity of 1 to 200 cSt is poured over thesubstrate and spread over the surface of the substrate in the form of afilm to a predetermined thickness. In this state, the liquid compositionis maintained at room temperature to 100° C. under a reduced pressure of2 to 5 Pa for 5 to 10 minutes in such a manner that air should not becontained in the liquid composition filled on the substrate in order toremove bubbles and dissolved oxygen contained in the liquid. Then, themold having predetermined fine irregularities in the surface is pressedagainst the liquid composition in the form of a film and kept at apressure of 0.5 to 120 kg/cm² and a temperature of 160 to 350° C. for 60seconds to 60 minutes or pressed against the liquid composition at theabove pressure and kept at 20 to 100° C. for 60 seconds to 30 minuteswhile it is exposed to ultraviolet radiation at an irradiation intensityof 1.0 to 50 mW/cm² at an exposed site in this state to almost completethe polymerization reaction of the liquid composition in order to cureit. In the case of exposure to ultraviolet radiation, at least one ofthe substrate and the mold is made from a material which transmitsultraviolet radiation. Then, by stripping off and removing the mold, apolydimethylsiloxane film which is a cured film having irregularities inthe surface which are the inversion of the irregularities of the mold isformed in such a state that it is adhered to the surface of thesubstrate. Then, the film is heated at 180 to 250° C. under normalpressure or a reduced pressure of 2 to 5 Pa for 15 to 350 minutes asrequired to vaporize the residual photopolymerization initiator andunpolymerized product contained in the polysiloxane film with the resultthat the film is slightly shrunken in volume in a thickness direction tobecome a compact film. An article such as an optical element coveredwith a film having a surface configuration which is the inversion of thesurface configuration of the mold is obtained.

A release film made from gold (Au) is preferably formed on the moldingsurface of the mold used in the present invention. Since gold hasexcellent releasability for a sol-gel material, mechanical strength highenough to withstand pressure applied to the sol-gel material, heatresistance, corrosion resistance and oxidation resistance, it isexcellent as a release film. When the thickness of the gold release filmis too small, the number of times of re-use becomes small and when thethickness of the film is too large, mold transferability deteriorates.Therefore, the thickness of the release film is preferably 200 to 1,000nm, more preferably 400 to 600 nm. Since the release film has higherreleasability as its surface becomes smoother, it is preferably formeduniform and smooth by sputtering, vacuum deposition, electrolessplating, electrolytic plating or hot foil stamping.

It is preferred to form an adhesion enhancing layer made from at leastone metal selected from the group consisting of platinum (Pt), copper(Cu), palladium (Pd) and silver (Ag) under the gold (Au) release film,that is, between the surface of the mold substrate and the above releasefilm. Specifically, a platinum (Pt), copper (Cu), palladium (Pd) orsilver (Ag) layer or an alloy layer thereof is formed on the moldingsurface of the mold substrate to a predetermined thickness before arelease film is formed on the surface. The adhesion enhancing layeradheres firmly the release film to the molding surface of the mold andserves as a protective layer for the formation of a pure release film bypreventing the molding surface layer (for example, silicon) of the moldsubstrate from being mixed with the release film at the time of formingthe release film. A metal which is excellent in adhesion to the moldingsurface of the mold substrate and the protection of the surface isplatinum (Pt). When the thickness of the adhesion enhancing layer is toosmall, adhesion between the release film and the molding surface of themold substrate cannot be increased and the release film is not made frompure gold. When the thickness is too large, the predeterminedconfiguration of the molding surface of the mold substrate changesdisadvantageously. Therefore, the adhesion enhancing layer has athickness of preferably 50 to 400 nm, more preferably 100 to 200 nm. Theadhesion enhancing layer is preferably formed uniform and smooth bysputtering, vacuum deposition, electroless plating or electrolyticplating.

At least the molding surface of the above mold substrate is made from atleast one material selected from the group consisting of titanium (Ti),aluminum (Al), silicon (Si) and oxides thereof. The mold substrate maybe made from titanium, aluminum, silicon, titanium oxide, aluminum oxideor silicon oxide, or may have a prime coat made from at least onematerial selected from the group consisting of titanium (Ti), aluminum(Al), silicon (Si) and oxides thereof on the surface (surface to becovered with a release film) of a core material of silicon, glass(including quartz glass), resin, metal or composite thereof. When themolding surface of the mold substrate is made from the above material,the release film and the adhesion enhancing layer firmly adhere to themold substrate, whereby there is no possibility that the release filmwill peel off from the mold and durability improves. The prime coat hasa thickness of preferably 20 to 300 nm, more preferably 50 to 100 nm.The prime coat is preferably formed uniform and smooth by sputtering,vacuum deposition, electroless plating or electrolytic plating. Anexample of the mold substrate is what is obtained by vacuum depositingtitanium on a core member made from silicon or quartz glass.

A material having an expansion coefficient close to that of the releasefilm is preferably selected as the material of the above core member.The core member made from a resin has advantages that it can be finelyprocessed easily and can be easily molded into a desired form. A glassor metal core member has high heat resistance and mechanical strengthand excellent durability.

The mold in the present invention has projections or depressions in itsmolding surface. The projections and depressions are, for example,spherical, conical, pyramid-like or slit-like having a desired section.Any number of spherical, conical or pyramid-like projections may beformed in the entire surface or part of the release film. When slits areformed as depressions, any number of linear or curved slits may beformed. When a plurality of slits are formed, they may be formedconcentrically or in a lattice form.

The substrate in the present invention is shaped like a flat board orcurved board. It is desired that the surface of the substrate have awarp (the length of thermal deformation in a direction perpendicular tothe surface per the unit length in the surface direction of thesubstrate) at 200° C. and 20° C. of ±5 μm or less per 1 cm. When thewarp is above this range, the film may peel off from the substrate orthe film may crack in the film molding step. Therefore, it is preferredto select the material, size and shape of the substrate.

Preferably, this substrate has a linear expansion coefficient of1.5×10⁻⁵/° C. or less. When the linear expansion coefficient of thesubstrate is larger than 1.5×10⁻⁵/° C., in the case of a plasticsubstrate having a high thermal expansion coefficient, such aspolypropylene (9 to 15×10⁻⁵/° C.), the film may peel off from thesurface of the substrate or the film may crack in the step of molding anorganopolysiloxane film. General inorganic glass has a linear expansioncoefficient of 1.5×10⁻⁵/° C. or less. At least the surface of thesubstrate is preferably made from an oxide. If the surface in contactwith the organopolysiloxane film of the substrate is not made from anoxide, the adhesion strength of the substrate will lower in the step ofmolding a film, whereby the film will readily peel off from thesubstrate. Preferred examples of the material of the substrate includeoxide glasses such as silicate-based glass exemplified by float glass,borate-based glass and phosphate-based glass, quartz, ceramics, silicon,metals such as aluminum, epoxy resin and glass fiber reinforcedpolystyrene. Although the organopolysiloxane film does not adhere to ametal as it is, when the surface of a metal is treated with an oxidizingagent, it can be used as the substrate.

When a transparent object which transmits light having a desiredwavelength, such as visible range, ultraviolet range or infrared rangeis used as the substrate in the present invention, the article obtainedby the present invention can function as a transmission type opticalelement such as a lens array, diffraction grating (such as an echelettediffraction grating, echelon diffraction grating or echelle diffractiongrating) or Fresnel lens. When a transparent or non-transparent objectis used as the substrate, a reflection type optical element such as adiffraction grating, diffuser or Fresnel mirror, or other informationrecording medium such as CD-ROM can be obtained by forming a metal (suchas aluminum or silver) or dielectric film (such as magnesium fluoride ortitanium oxide) on the organopolysiloxane film.

When an inorganic substrate made from oxide glass such as silicate-basedglass, borate-based glass or phosphate-based glass, quartz, ceramic,silicon or metal such as aluminum is used as the substrate in thepresent invention, it is desired that a film, preferably a 5 to 200nm-thick film containing a silane coupling agent be formed by applying asurface treating composition containing a silane coupling agent to thesurface of the substrate before use.

The silane coupling agent is, for example, a silicon compound having anorganic functional group represented by the following formula (3):

R⁴R⁵ _(k)Si(R⁶)_(3−k)  (3)

wherein R⁴ is an organic group having a methacryl group, acryl group,epoxy group, allyl group, mercapto group or amino group, or a vinylgroup, R⁵ is an alkyl group such as methyl group or ethyl group, R⁶ is agroup or atom having hydrolyzability, and k is 0 or 1. Examples of theabove organic group having a methacryl group, acryl group, epoxy group,ally group, mercapto group or amino group include organic groupsobtained by substituting the hydrogen of an alkyl group (such as alkylgroup having 1 to 3 carbon atoms) by these groups. R⁶ (group or atomhaving hydrolyzability) is an alkoxyl group, alkoxyalkoxyl group,acetoxyl group, amide group, oxime group, propenoxyl group or chlorineatom.

Illustrative examples of the silicon compound represented by the aboveformula (3) as the silane coupling agent are given below. They includeacryl functional silanes, epoxy functional silanes, methacryl functionalsilanes, allyl functional silanes, mercapto functional silanes, aminofunctional silanes and vinyl functional silanes. The acryl functionalsilanes (R⁴ in the above formula (3) is an organic group having an acrylgroup) include 3-acryloxypropyl trimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-acryloxypropyl triethoxysilane and3-acryloxypropylmethyl diethoxysilane. The epoxy functional silanes (R⁴in the above formula (3) is an organic group having an epoxy group)include 3-glycidoxypropyl trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyl triethoxysilane. Themethacryl functional silanes (R⁴ in the above formula (3) is an organicgroup having a methacryl group) include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyl triethoxysilane,3-methacryloxypropylmethyl dimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxyundecyl trimethoxysilane and3-methacryloxyethyloxypropyl trimethoxysilane. The allyl functionalsilanes (R⁴ in the above formula (3) is an organic group having an allygroup) include allyl triethoxysilane, allyl trichlorosilane, allyltrimethoxysilane and allylphenyl dichlorosilane. The mercapto functionalsilanes (R⁴ in the above formula (3) is an organic group having amercapto group) include 3-mercaptopropyl trimethoxysilane. The aminofunctional silanes (R⁴ in the above formula (3) is an organic grouphaving an amino group) include 3-aminopropyl trimethoxysilane. The vinylfunctional silanes (R⁴ in the above formula (3) is a vinyl group)include vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tris(β-methoxyethoxy)silane, vinyl triacetoxysilane and vinyltrichlorosilane.

The surface treating composition may contain a compound represented bythe following formula (4):

M(R⁷)_(p)  (4)

wherein M is silicon, titanium, zirconium or aluminum, R⁷ is a group oratom having hydrolyzability, and p is 4 when M is silicon, titanium orzirconium and 3 when M is aluminum, or a hydrolyzate thereof, besidesthe silane coupling agent.

Examples of R⁷ (group or atom having hydrolyzability) include alkoxylgroup, alkoxyalkoxyl group, acyloxy group, acetoxyl group and chlorineatom. By containing this compound, the film containing a silane couplingagent formed on the surface of the substrate is more firmly adhered tothe surface of the substrate. When the content of the compound is toolow, the effect of increasing this adhesion is small and when thecontent is too high, the effect of the silane coupling agent itselflowers. Therefore, the compound represented by the formula (4) (or itshydrolyzate) is preferably contained in the surface treating compositionin an amount of 5 to 50 parts by weight based on 100 parts by weight ofthe silane coupling agent.

Out of the compounds represented by the above formula (4), compounds inwhich M is silicon include tetraethoxysilane, tetramethoxysilane,tetra-2-methoxyethoxysilane, tetraacetoxysilane and tetrachlorosilane.

Out of the compounds represented by the above formula (4), compounds inwhich M is titanium include tetramethoxy titanium, tetraethoxy titanium,tetraisopropoxy titanium, tetraisopropoxy titanium isopropanol complex,tetra-n-propoxy titanium, tetraisobutoxy titanium, tetra-n-butoxytitanium, tetra-sec-butoxy titanium, tetra-t-butoxy titanium,tetra(2-ethylhexyloxy)titanium and tetrastearyloxy titanium.

Out of the compounds represented by the above formula (4), compounds inwhich M is zirconium include tetramethoxy zirconium, tetraethoxyzirconium, tetraisopropoxy zirconium, tetra-n-propoxy zirconium,tetraisopropoxy zirconium-isopropanol complex, tetraisobutoxy zirconium,tetra-n-butoxy zirconium, tetra-sec-butoxy zirconium and tetra-t-butoxyzirconium.

Out of the compounds represented by the above formula (4), compounds inwhich M is aluminum include trimethoxy aluminum, triethoxy aluminum,triisopropoxy aluminum, tri-n-propoxy aluminum, triisobutoxy aluminum,tri-n-butoxy aluminum, tri-sec-butoxy aluminum and tri-t-butoxyaluminum.

The hydrolyzate of the compound represented by the above formula (4)include hydrolyzates obtained by substituting some or all of R⁷'s in theabove compound by a hydroxyl group and hydrolyzates obtained by thenatural condensation of some of the substituted hydroxyl groups. Thesehydrolyzates can be easily obtained by hydrolyzing the compound in amixed solvent of water and an alcohol in the presence of an acid.

The surface treating composition comprises an alcohol as an essentialcomponent and further an acid catalyst and water as optional components,in addition to the above silane coupling agent and optionally thecompound represented by the above formula (4) (or a hydrolyzate thereof)to be contained.

The above acid catalyst is not always necessary when the above silanecoupling agent and the compound represented by the above formula (4) arealready hydrolyzed. However, when they are not hydrolyzed, the acidcatalyst is preferably contained as a catalyst for the hydrolysis anddehydration of the above components. Although the type of the acidcatalyst is not particularly limited, an acid catalyst which is easilyvaporized by drying and hardly remains in the film is preferred becausethe film can be made hard. Examples of the acid catalyst includehydrochloric acid, nitric acid, acetic acid, hydrofluoric acid, formicacid and trifluoroacetic acid. The amount of the acid is preferably 10⁻⁵to 10 parts by weight, more preferably 10⁻³ to 1 part by weight based on100 parts by weight of the silane coupling agent.

The above water is not always necessary when the above silane couplingagent and the compound represented by the above formula (4) are alreadyhydrolyzed. However, when they are not hydrolyzed, water is preferablycontained in the surface treating composition for the hydrolysis ofthese components. The amount of water is 10 to 300 parts by weight basedon 100 parts by weight of the silane coupling agent, including a watersolvent for the compound represented by the above formula (4) and watercontained in the alcohol to be described hereinafter as an impurity.

Although the above alcohol solvent is not particularly limited, it is,for example, methanol, ethanol, 1-propanol, 2-propanol, butyl alcohol oramyl alcohol. Out of these, chain saturated monohydric alcohols having 3or less carbon atoms such as methanol, ethanol, 1-propanol and2-propanol are preferred because their vaporization rates at normaltemperature are high. The amount of the alcohol, which differs accordingto coating technique and desired film thickness, is preferably 500 to10,000 parts by weight based on 100 parts by weight of the silanecoupling agent.

The technique for applying the surface treating composition is notparticularly limited. Dip coating, flow coating, curtain coating, spincoating, spray coating, bar coating, roll coating or brush coating maybe used.

The surface treating composition is applied at a temperature of 0 to 40°C., for example, room temperature and a relative humidity of 40% orless. After application, the coating film is dried at a temperature of 0to 40° C., for example, room temperature and a relative humidity of 40%or less for 10 seconds to 20 minutes. Subsequently, it may be heated ata temperature higher than room temperature to 30° C. for 30 seconds to10 minutes as required.

The preferred composition of the surface treating composition based onthe silicon compound represented by the above formula (3) is as follows.

Silicon compound represented by the formula (3): 100 parts by weight

Compound represented by the above formula (4): 5 to 50 parts by weight

Water: 10 to 300 parts by weight

Acid catalyst: 10⁻⁵ to 10 parts by weight

Solvent (alcohol): 500 to 10,000 parts by weight

According to the present invention, an organopolysiloxane film havingheat resistance high enough to stand a temperature of 350° C., a maximumthickness (thickness measured at a depression portion in the surface) of1 μm to 1 mm, preferably 20 to 150 μm, a refractive index of 1.50 to1.54 which is close to the refractive index of ordinary glass and finesurface irregularities, for example, those having a predetermined heightof 5 to 500 μm and a predetermined width (pitch of irregularities) of 1to 500 μm is formed on the substrate which is shaped like a flat boardor curved board and whose surface has been treated with a silanecoupling agent.

The dimethylpolysiloxane film which comprises this film contains 10 to50 wt % of a methyl group, 1 to 30 wt % of a polymerized segment of apolymerizable organic group and 45 to 89 wt % of a Si—O structuralsegment. The total of the methyl group and the polymerized segment ofthe polymerizable organic group is 11 to 55 wt %.

This film is elastic (little brittle), has high strength and hardlycracks. Since bubbles formed by molding are not seen in the film and theshrinkage of the film at the time of molding is small, excellenttransferability with extremely high dimensional accuracy of fineirregularities in the surface of the film can be achieved. Stated morespecifically, when a large number of projections having a height of 20to 100 μm, for example, are formed, height variations among theprojections in the surface of the film are 1 μm or less. The deviationof the interval between projections in the surface of the film from thatof the mold is measurement accuracy (0.2 μm) or less.

When the optical element of the present invention is used as areflection type optical element, a reflection increasing film ispreferably formed on the surface of the optical element. The reflectionincreasing film is a thin film of metal such as gold, silver, platinumor aluminum or a laminate formed by alternately piling up dielectricthin films having a high refractive index and a low refractive index.The dielectric thin film having a high refractive index is made fromtantalum oxide, titanium oxide, zirconium oxide or hafnium oxide. Out ofthese, tantalum oxide stable to laser beams is preferably used. Thedielectric thin film having a low refractive index is made from silicaor magnesium fluoride. A combination of a metal thin film and adielectric multi-layer film may be used. The refractive index andthickness of the thin film are adjusted such that the operationwavelength of the reflection type optical element and the wavelength ofthe reflection peak of the reflection increasing film agree with eachother. When the optical element is used as a transmission type opticalelement, an anti-reflection film is preferably formed at the interfacewith air. The anti-reflection film is a laminate formed by alternatelypiling up dielectric thin films having a high refractive index and a lowrefractive index or an anti-reflection structure having a fine cyclicstructure of 1 μm or less.

The coating film of the article having a predetermined surfaceconfiguration such as an optical element obtained by the presentinvention is made from a matrix containing silicon and oxygen, some ofthe above silicon atoms are bonded to other silicon atoms through afirst polyhydrocarbon group having at least 4 carbon atoms (such as agroup obtained by polymerizing two acryloxypropyl groups), and some ofthe above silicon atoms are directly bonded to a second monohydrocarbongroup (methyl group). Since an organic segment and an inorganic segmentare thus bonded together, a material for an optical element havingexcellent heat resistance and moldability is provided. By changing thecontents of the first polyhydrocarbon group and the secondmonohydrocarbon group, the refractive index of the transmission typeoptical element can be adjusted. When the total content of the firstpolyhydrocarbon group and the second monohydrocarbon group is too high,they exert an influence upon heat resistance. Therefore, the totalcontent is preferably 55 wt % or less.

The first polyhydrocarbon group combines the first silicon atom with thesecond silicon atom and may contain a hetero atom such as oxygen atom,nitrogen atom or sulfur atom in addition to carbon atom and hydrogenatom. The oxygen atom and nitrogen atom serve to increase the bondingforce of the matrix and improve bonding force between the matrix and thesurface of the substrate through chemical bonding such as ion bonding orhydrogen bonding. The second monohydrocarbon group may contain a heteroatom such as oxygen atom, nitrogen atom or sulfur atom in addition tocarbon atom and hydrogen atom. It may also contain fluorine atom oranother halogen atom. By using fluorine atom, the refractive index canbe reduced and hydrophobic nature can be provided, thereby making itpossible to improve the water resistance of the optical element.

EXAMPLES

Examples are provided to further illustrate the present invention.

The articles in Examples 1 to 6 were substantially produced by thefollowing process: (1) preparation of a polydimethylsiloxane solution,(2) application of the solution to a mold or substrate anddegasification, (3) assembly/exposure and mold release (assembly/heatingand mold release in Example 6, and (4) final heating (baking).

The articles in Examples 7 to 13 were substantially produced by thefollowing process: (1) preparation of a polydimethylsiloxane solution,(2) application of a surface treating composition comprising a silanecoupling agent to an inorganic substrate, (3) application of thesolution to a mold or substrate and degasification, (4)assembly/exposure and mold release, and (5) final heating (baking).

Preparation of Polydimethylsiloxane Solution A:

4 g of a polydimethylsiloxane having acryloxypropyl at both terminals(10 recurring units represented by —((CH₃)₂Si—O)—) and 0.04 g of aphotopolymerization initiator,[2-hydroxy-2-methyl-1-phenylpropane-1-one], were fed to a brown samplebottle and stirred for 3 hours to prepare a stock solution A.

Preparation of Polydimethylsiloxane Solution B:

4 g of a polydimethylsiloxane having methacryloxypropyl at bothterminals (10 recurring units represented by —((CH₃)₂Si—O)—) and 0.04 gof a photopolymerization initiator,[2-hydroxy-2-methyl-1-phenylpropane-1-one], were fed to a brown samplebottle and stirred for 3 hours to prepare a stock solution B.

Preparation of Polydimethylsiloxane Solution C:

4 g of a polydimethylsiloxane having methacryloxypropyl at bothterminals (30 recurring units represented by —((CH₃)₂Si—O)—) and 0.04 gof a photopolymerization initiator,[2-hydroxy-2-methyl-1-phenylpropane-1-one], were fed to a brown samplebottle and stirred for 3 hours to prepare a stock solution C.

Preparation of Polydimethylsiloxane Solution D:

4 g of a copolymer of (epoxycyclohexylethyl)methylsiloxane which is abranched epoxysiloxane and dimethylsiloxane (120 recurring unitsrepresented by —((CH₃)₂Si—O)— and 5 (epoxycyclohexylethyl)methylsiloxaneunits) and 0.1 g of a 20 wt % isopropyl alcohol solution of aphotopolymerization initiator [diphenyliodoniumtetrakis(pentafluorophenyl)borate], were fed to a brown sample bottleand stirred for 3 hours to prepare a stock solution D.

Preparation of Silane Coupling Agent Solution E:

A mixture of 0.434 g of 3-acryloxypropyl trimethoxysilane and 0.868 g ofHAS-10 (manufactured by Colcoat Co., Ltd., solid content of 10%(hydrolyzate of tetraethoxysilane)) was dissolved in a mixed solution of8.598 g of ethanol and 0.0998 g of a nitric acid aqueous solution havinga concentration of 0.22 mol/l and stirred for 3 hours to prepare asilane coupling agent solution E.

Preparation of Silane Coupling Agent Solution F:

A mixture of 0.541 g of 2-(3,4-epoxy)ethyl trimethoxysilane and 0.868 gof HAS-10 (manufactured by Colcoat Co., Ltd., solid content of 10%(hydrolyzate of tetraethoxysilane)) was dissolved in a mixed solution of8.491 g of ethanol and 0.0998 g of a nitric acid aqueous solution havinga concentration of 0.22 mol/l and stirred for 3 hours to prepare asilane coupling agent solution F.

Preparation of Silane Coupling Agent Solution G:

A mixture of 0.541 g of 2-(3,4-epoxy)ethyl trimethoxysilane and 0.087 gof tetraethoxysilane was dissolved in a mixed solution of 9.272 g ofethanol and 0.0998 g of a nitric acid aqueous solution having aconcentration of 0.22 mol/l and stirred for 3 hours to prepare a silanecoupling agent solution G.

Preparation of Silane Coupling Agent Solution H:

0.541 g of 2-(3,4-epoxy)ethyl trimethoxysilane was dissolved in a mixedsolution of 9.272 g of ethanol and 0.0998 g of a nitric acid aqueoussolution having a concentration of 0.22 mol/l and stirred for 3 hours toprepare a silane coupling agent solution G.

Application of a Solution to a Mold or Substrate and Degasification:

In the mold casting process, the above solution A was poured over thesurface of a transparent mold to form a 50 μm to 1 mm-thick layer whichwas then degasified at room temperature under a reduced pressure of 3 to5 Pa for 5 minutes. A photocurable film (viscosity: 180 cSt) could beformed on the mold or substrate by this degasification.

Assembly, Exposure and Mold Release:

In the case of the mold casting process, the coating film was thencontacted to the surface of the substrate and exposed to ultravioletradiation for 1 to 30 minutes in this state to be assembled with thesubstrate. In Example 6, the film was heated at 200° C. for 15 minutesin place of exposure to ultraviolet radiation. After the coating filmwas completely cured, the mold was stripped off and removed from thesubstrate. As a result, a board with fine irregularities in the surfacehaving a film to which the surface configuration of the mold had beentransferred and which was adhered to the surface of the substrate wasobtained.

In the case of the substrate casting process, a transparent mold waspressed against the above coating film and exposed to ultravioletradiation for 1 to 30 minutes to assemble the coating film with thesubstrate. Thereafter, the mold was removed. As a result, a board withfine irregularities in the surface having a film to which the surfaceconfiguration of the mold had been transferred and which was adhered tothe surface of the substrate was obtained.

Final Heating:

The board having fine irregularities in the surface obtained by removingthe mold was heated at 250° C. under a reduced pressure of 2 to 3 Pa for60 minutes to obtain an article having an uneven surface. Theperformance and characteristic properties of the obtained article havingan uneven surface were evaluated by the following methods.

Measurement of Height Variations Among Projections:

The measurement of height variations among the projections of theoutermost layer was carried out by a laser microscope.

Measurement of Heat Resistance and Optical Properties:

After a heat resistance test was made on articles having an unevensurface obtained in Examples and Comparative Examples by maintainingthem at 300° C. for 2 hours, they were returned to room temperature tocheck cracking in order to evaluate their heat resistances. Using aninterference meter (He-Ne laser, λ=633 nm), the wave aberration of adiffraction grating, the spherical aberration of a microlens and theamount of reflection within the substrate at an incident angle of 6°upon the surface of the substrate were measured after and before theheat resistance test for evaluation. Also, the d-ray refractive index ofthe film portion was measured with an Abbe refractometer.

Adhesion Test:

The surface of the substrate having a film was cut with a knife to form11 parallel cut lines in both longitudinal and transverse directions atintervals of 1 mm in order to form 100 squares and Cellophane adhesivetape was affixed to the substrate and stripped off. The number ofsquares adhered to the substrate and not removed was counted andexpressed in percentage.

Chemical Resistance Test:

After the substrate having a film was immersed in an alkali solution for1 hour, ethanol for 1 hour and boiling water for 1 hour, the film wasobserved with the naked eye to judge the separation of the film.

Preparation of Substrate 1:

A 50 mm-square quartz glass board having a thickness of 3.0 mm (linearexpansion coefficient: 5.5×10⁻⁷/° C.) was ultrasonically cleaned with analkali and then with pure water to prepare a substrate 1.

Preparation of Substrate 2:

A 2.5 mm-square soda lime glass board having a thickness of 3.0 mm(linear expansion coefficient: 1.0×10⁻⁵/° C.) was ultrasonically cleanedwith an alkali and then with pure water to prepare a substrate 2.

Surface Treatment by Silane Coupling Agent Solution:

The silane coupling agent solution E or F was applied to the surface ofthe above substrates 1 and 2 by spin coating at a revolution of 1,500rpm for 15 seconds and heated at 120° C. for 15 minutes. The thicknessof each silane coupling agent coating was 100 nm. Surface treatmentswith the silane coupling agent solutions E, F, G and H are designated assurface treatments 1, 2, 3 and 4, respectively.

Example 1

A 50 mm-square quartz glass substrate having a thickness of 3.0 mm(linear expansion coefficient: 5.5×10⁻⁷/° C.) as a glass substrate wasultrasonically cleaned with an alkali and then with pure water. Usingthe solution A, a film was formed on one side of this quartz glasssubstrate to form a board having fine irregularities in the surface inaccordance with the mold casting method. A glass mold (50 mm×50 mm witha thickness of 5 mm) having about 2,500 depressions with a curvatureradius of 1,750 μm, a lens diameter of 1,000 μm and a depression depthof 73 μm, consisting of 50 spherical depressions formed close to oneanother in a longitudinal direction and 50 spherical depressions formedclose to one another in a transverse direction, was used as the mold. A80 nm-thick titanium (Ti) film was formed as a prime layer on thesurface of the mold to improve releasability and then a 170 nm-thickplatinum (Pt) film was formed on the titanium film as a protectivelayer. Thereafter, this mold was placed in a vacuum sputtering deviceand a 53 nm-thick gold (Au) film was formed as a release film on theplatinum film by sputtering to obtain a mold. After final heating, anorganopolysiloxane film having a thickness of the most thin region ofabout 20 μm and a maximum thickness from the top of the sphericalportion of 91.5 μm was formed on the quartz glass substrate and theabove number of convex microlenses were formed in the surface of thefilm. The thickness of the coating of the solution A was about 100 μm,degasification was carried out gradually at room temperature for 5minutes after coating, and the final pressure was 5 Pa. Exposure toultraviolet radiation was carried out from the substrate side at anintensity of 10 mW/cm² and room temperature for 10 minutes and finalheating was carried out at 3 Pa and 250° C. for 60 minutes.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. A methyl group, an acrylpolymerized segment [—(CH₂)₃OCO(CH₂)₄COO(CH₂)₃—] and Si—O structuralsegment were contained in the film in amounts of 32.7 wt %, 20.7 wt %and 46.6 wt %, respectively. The focusing distances of the microlensesranged from 3,297 to 3,300 μm. As for the heights of the projections ofthe board having a film (board having fine irregularities in thesurface), when 100 spherical projections selected at random weremeasured, the average height of the projections was 71.5 μm and itsstandard deviation was 0.12 μm. The shrinkage factor of the cured filmcalculated from these values was about 2%, the average sphericalaberration measured by a He-Ne laser (λ=633 nm) of the microlenses was0.05 λ and its standard deviation was 0.001 λ. When the heat resistanceof this board was evaluated, the film did not crack or peel off, and thefocusing distances of all the projections ranged from 3,297 to 3,300 μmwhich was the same as before the heat resistance test. When the diameterof a convergent beam spot was measured by inputting parallel lightvertically from the opposite side of the film, the diameters of theconvergent beam spots of all the convex lenses were 3 μm or less whichwas the same as before the heat resistance test.

Comparative Example 1

When a board having fine irregularities in the surface was formed in thesame manner as in Example 1 using the same substrate and mold as inExample 1 except that an acrylic acid monomer was used without a solventin place of the solution A used in Example 1, the thickness of the mostthin region of the film was about 35 μm. As for the heights of theprojections of this board, when 100 spherical projections selected atrandom were measured, the average shrinkage factor was 6% which waslarger than that of Example 1. Similarly, the average sphericalaberration measured at 100 points was 0.3 λ which was larger (6 times)than in Example 1 and its standard deviation was 0.01 λ which was 10times larger than in Example 1. Since the projections greatly differedfrom one another in height and were not spherical, the shape of theconvergent beam spot was bad with a diameter of 10 μm. The focusingdistances of the projections greatly varied from 2,900 to 3,600 μm.Further, when heat resistance was evaluated in the same manner as inExample 1, the film cracked or peeled off, the board greatly deformed,and the focusing distance and spherical aberration could not beevaluated.

Comparative Example 2

0.075 mol of phenyl triethoxysilane, 0.1 mol of dimethyl diethoxysilaneand 0.063 mol of (3,3,3-trifluoropropyl)trimethoxysilane were placed ina beaker and stirred. 0.25 mol of ethanol was added to this solution andstirred, and an aqueous solution prepared by dissolving 0.1 wt % offormic acid in 1.75 mols (31.5 g) of water was further added to theresulting solution and stirred for 2 hours to prepare a solution. Thissolution was used in place of the solution A used in Example 1 to form aboard having fine irregularities in the surface in the same manner as inExample 1. The thickness of the most thin region was about 50 μm. As forthe heights of the projections of this board, when 100 sphericalprojections selected at random were measured, the average shrinkagefactor was 10% which was larger than in Example 1. The average sphericalaberration of the 100 projections was 0.75 λ which was larger (15 times)than in Example 1 and its standard deviation was 0.15 λ which was 15times larger than in Example 1. Since the projections greatly differedfrom one another in height and were not spherical, the shape of theconvergent beam spot was bad with a diameter of 12 μm. The focusingdistance greatly varied from 3,000 to 3,500 μm but when the heatresistance was evaluated in the same manner as in Example 1, the filmdid not crack or peel off and the focusing distance and the sphericalaberration remained the same as the values before the test.

Example 2

A 2.5 cm-square soda lime glass substrate having a thickness of 3.0 mm(linear expansion coefficient: 1.0×10⁻⁵/° C.) was ultrasonically cleanedwith an alkali and then with pure water as a glass substrate. Using thesolution B, a film was formed on one side of this glass substrate toform a board having fine irregularities in the surface in accordancewith the substrate casting process. A glass mold having 120 2.5 cm-longtub-like depressions with a substantially semi-circular arc sectionhaving a curvature radius of 100 μm and disposed close to one another ina longitudinal direction was coated with a release film as in Example 1.After final heating, an organopolysiloxane film having a thickness ofthe most thin region of about 30 μm and a maximum thickness from the topof the semi-circular portion of 130 μm was formed on the soda lime glasssubstrate and 120 columnar convex microlenses were formed in the surfaceof the film. The thickness of the coating film of the solution A wasabout 150 μm, degasification was carried out gradually at roomtemperature for 5 minutes after coating, and the final pressure was 5Pa. Exposure to ultraviolet radiation was carried out from the substrateside at an intensity of 10 mW/cm² and room temperature for 10 minutesand final heating was carried out at 3 Pa and 250° C. for 60 minutes.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. A methyl group,methacryl polymerized segment and Si—O structural segment were containedin the film in amounts of 32.0 wt %, 22.5 wt % and 45.5 wt %,respectively. As for the heights of the columnar projections of thissubstrate, when 20 projections selected at random were measured, theaverage height from the surface of the substrate was 130 μm and itsstandard deviation was 0.11 μm. When the heat resistance of thissubstrate was evaluated, the film did not crack and no change was seenin the appearance, projection height, its standard deviation andprojection pitch of the film.

Example 3

A 2.5 cm-square soda lime glass substrate having a thickness of 3.0 mm(linear expansion coefficient: 1.0×10⁻⁵/° C.) was ultrasonically cleanedwith an alkali and then with pure water as a glass substrate. A 2.5cm-square silicon reflection type echelon diffraction grating having anaverage thickness of 2.0 mm (about 1,000 irregularities (parallel linearprojections) were formed in the surface of a silicon substrate bymasking or etching, inclined surfaces on the both sides of each mountainportion agreed with the plane (1,1,1) of a silicon crystal, projectionheight of 20.15 μm, projection width of 14.3 μm, interval betweenadjacent gratings (interval between peaks) of about 24.7 μm, flatportion at the peak (length of the remaining unetched portion of about5.0 μm)) was prepared as the mold. This mold was coated with the samerelease film as in Example 1. A board having fine irregularities in thesurface which was a reflection type echelon diffraction grating having athickness of the most thin region of about 40 μm was formed using theabove substrate, mold and solution A in accordance with the mold castingprocess. The thickness of the coating of the solution A was about 150μm, degasification was carried out gradually at room temperature for 5minutes after coating, and the final pressure was 5 Pa. Exposure toultraviolet radiation was carried out at an intensity of 10 mW/cm² androom temperature for 10 minutes and final heating was carried out at 3Pa and 250° C. for 60 minutes.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. As for the heights ofthe projections of this board having fine irregularities in the surface,when 10 linear projections selected at random were measured at 100points at intervals of 9 mm in a longitudinal direction, the averageheight was 0.2 μm and its standard deviation was 0.05 μm. A reflectiontype echelon diffraction grating which was a board having fineirregularities in the surface capable of efficiently and selectivelyblazing 1.55 μm light and 1.30 μm light as diffracted light of 26-thorder and diffracted light of 31-st order, respectively, was thusobtained. The average wave aberration measured by an He-Ne laser (λ=633nm) of this reflection type echelon diffraction grating was 0.05 λ andits standard deviation was 0.001 λ. When the heat resistance of thisboard having fine irregularities in the surface was evaluated, the filmdid not crack and no change was seen in the appearance, projectionheight, its standard deviation, diffraction pattern and wave aberrationof the film from the values before the heat resistance test.

Example 4

A 2.5 cm-square soda lime glass substrate having a thickness of 3.0 mm(linear expansion coefficient: 1.0×10⁻⁵/° C.) was ultrasonically cleanedwith an alkali and then with pure water as a glass substrate. A 3.0cm-square resin blazed diffraction grating having a thickness of 5 mm(pitch of 1.1 μm, groove depth of 0.8 μm, saw-toothed) was prepared asthe mold. The surface of this diffraction grating was plated with Cr toa thickness of 80 nm in order to improve the releasability of thesurface when it was used as the mold and then a 5 nm-thick Au layer wasformed on the surface by sputtering. A board having fine irregularitiesin the surface which was a reflection type blazed diffraction gratinghaving a thickness of the most thin region of about 3 μm was formedusing the above substrate, mold and solution C in accordance with themold casting process. The thickness of the coating of the solution C wasabout 150 μm, degasification was carried out gradually at roomtemperature for 5 minutes after coating, and the final pressure was 5Pa. Exposure to ultraviolet radiation was carried out at an intensity of10 mW/cm² and room temperature for 10 minutes and final heating wascarried out at 3 Pa and 250° C. for 60 minutes.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. A methyl group,methacryl polymerized segment and Si—O structural segment were containedin the film in amounts of 36.8 wt %, 9.8 wt % and 53.4 wt %,respectively. The thickness of each projection portion was 3.0 μm, thethickness of each depression portion was 2.2 μm and the refractive indexwas 1.48. As for the heights of the projections of this board havingfine irregularities in the surface, when 10 linear projections selectedat random were measured at 100 points at intervals of 9 mm in alongitudinal direction, the average height was 3.0 μm and its standarddeviation was 0.05 μm. A reflection type blazed diffraction gratingwhich was a board having fine irregularities in the surface capable ofefficiently and selectively blazing the primary diffracted light of 1.55μm light was thus obtained. The average wave aberration measured by aHe-Ne laser (λ=633 nm) of this diffraction grating was 0.025 λ and itsstandard deviation was 0.001 λ. When the heat resistance of this boardhaving fine irregularities in the surface was evaluated, the film didnot crack and no change was seen in the appearance, projection height,its standard deviation, diffraction pattern and wave aberration of thefilm from the values before the heat resistance test.

Example 5

A 2.5 cm-square soda lime glass substrate having a thickness of 3.0 mm(linear expansion coefficient: 1.0×10⁻⁵/° C.) was ultrasonically cleanedwith an alkali and then with pure water as a glass substrate. A boardhaving fine irregularities in the surface which was a reflection typeechelon diffraction grating having a thickness of the most thin regionof about 40 μm was formed using the same mold having a release coat asin Example 3, the above substrate and solution D in accordance with themold casting process. The thickness of the coating of the solution D wasabout 150 μm, degasification was carried out gradually at roomtemperature for 5 minutes after coating, and the final pressure was 5Pa. Exposure to ultraviolet radiation was carried out at an intensity of10 mW/cm² and room temperature for 10 minutes and final heating wascarried out at 3 Pa and 250° C. for 60 minutes.

The organopolysiloxane cured film of the board having fineirregularities in the surface manufactured as described above wastransparent and had a refractive index of 1.46. As for the heights ofthe projections of this board, when 10 linear projections selected atrandom were measured at 100 points at intervals of 9 mm in alongitudinal direction, the average height was 20.2 μm and its standarddeviation was 0.05 μm. A reflection type echelon diffraction gratingwhich was a board having fine irregularities in the surface capable ofefficiently and selectively blazing 1.55 μm light and 1.30 μm light asdiffracted light of 26-th order and diffracted light of 31-st order,respectively, was thus obtained. The average wave aberration measured bya He-Ne laser (λ=633 nm) of this reflection type echelon diffractiongrating was 0.05 λ and its standard deviation was 0.001 λ. When the heatresistance of this board having fine irregularities in the surface wasevaluated, the film did not crack and no change was seen in theappearance, projection height, its standard deviation, diffractionpattern and wave aberration of the film from the values before the heatresistance test.

Example 6

A 2.5 cm-square soda lime glass substrate having a thickness of 3.0 mm(linear expansion coefficient: 1.0×10⁻⁵/° C.) was ultrasonically cleanedwith an alkali and then with pure water as a glass substrate. A boardhaving fine irregularities in the surface which was a reflection typeechelon diffraction grating having a thickness of the most thin regionof about 40 μm was formed using the same mold having a release coat asin Example 3, the above substrate and solution D in accordance with themold casting process. The thickness of the coating of the solution D wasabout 150 μm, degasification was carried out gradually at roomtemperature for 5 minutes after coating, and the final pressure was 5Pa. After the coating was heated at 200° C. under a pressure of 15kg/cm² for 15 minutes and then cooled to room temperature over 10minutes, pressurization was stopped and the mold was removed. Finalheating was carried out at 3 Pa and 250° C. for 60 minutes.

The organopolysiloxane cured film of the board having fineirregularities in the surface manufactured as described above wastransparent and had a refractive index of 1.46. As for the heights ofthe projections of this board, when 10 linear projections selected atrandom were measured at 100 points at intervals of 9 mm in alongitudinal direction, the average height was 20.2 μm and its standarddeviation was 0.05 μm. A reflection type echelon diffraction gratingwhich was a board having fine irregularities in the surface capable ofefficiently and selectively blazing 1.55 μm light and 1.30 μm light asdiffracted light of 26-th order and diffracted light of 31-st order,respectively, was thus obtained. The average wave aberration measured bya He-Ne laser (λ=633 nm) of this reflection type echelon diffractiongrating was 0.05 λ and its standard deviation was 0.001 λ. When the heatresistance of this board having fine irregularities in the surface wasevaluated, the film did not crack and no change was seen in theappearance, projection height, its standard deviation, diffractionpattern and wave aberration of the film from the values before the heatresistance test.

Example 7

A board having fine irregularities in the surface was manufactured byforming a film on the surface of the substrate 1 subjected to thesurface treatment 1 using the solution A in accordance with the moldcasting process. A glass mold (50 mm×50 mm with a thickness of 5 mm)having about 2,500 spherical depressions with a curvature radius of1,750 μm, a lens diameter of 1,000 μm and a depression depth of 73 μm,consisting of 50 depressions formed close to one another in alongitudinal direction and 50 depressions formed close to one another ina transverse direction, was used as the mold. A 80 nm-thick titanium(Ti) film was formed on the surface of the mold as a prime layer toimprove releasability and then a 170 nm-thick platinum (Pt) film wasformed on the titanium film as a protective layer. This mold was placedin a vacuum sputtering device to form a 53 nm-thick gold (Au) film as arelease film on the platinum layer by sputtering to obtain a mold. Afterfinal heating, an organopolysiloxane film having a thickness of the mostthin region of about 20 μm and a maximum thickness from the top of thespherical portion of 91.5 μm was formed on the surface treated substrate1 and the above number of convex microlenses were formed in the surfaceof the film. The thickness of the coating of the solution A was about100 μm, gasification was carried out gradually at room temperature for 5minutes after coating, and the final pressure was 5 Pa. Exposure toultraviolet radiation was carried out from the substrate side at anintensity of 10 mW/cm² and room temperature for 10 minutes and finalheating was carried out at 3 Pa and 250° C. for 60 minutes.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. A methyl group, acrylpolymerized segment [—(CH₂)₃OCO(CH₂)₄COO(CH₂)₃—] and Si—O structuralsegment were contained in the film in amounts of 32.7 wt %, 20.7 wt %and 46.6 wt %, respectively. The focusing distances of the manufacturedconvex lenses (microlenses) ranged from 3,297 to 3,300 μm. As for theheights of the projections of this board having a film (board havingfine irregularities in the surface), when 100 spherical projectionsselected at random were measured, the average height was 71.5 μm and itsstandard deviation was 0.12 μm. The shrinkage factor calculated fromthese of the cured film was about 2%, the average spherical aberrationmeasured by a He-Ne laser (λ=633 nm) of the microlenses was 0.05 λ andits standard deviation was 0.001 λ. When the heat resistance of thisboard was evaluated, the film did not crack or peel off, the focusingdistances of all the projections ranged from 3,297 to 3,300 μm which wasthe same as before the heat resistance test. When the diameter of aconvergent beam spot was measured by inputting parallel light verticallyfrom the opposite side of the film, the diameters of the convergent beamspots of all the convex lenses were 3 μm or less which was the same asbefore the heat resistance test.

In an adhesion test, the adhesion of the film was 100% which proved thatthe film had high adhesive force. In a chemical resistance test, theseparation of the film was not observed.

Comparative Example 3

When a board having fine irregularities in the surface was manufacturedusing the same substrate 1 subjected to the surface treatment 1 and thesame mold as in Example 7 in the same manner as in Example 7 except thatan acrylic acid monomer was used without a solvent in place of thesolution A, the thickness of the most thin region was about 35 μm. Asfor the heights of the projections of this board, when 100 sphericalprojections selected at random were measured, the average shrinkagefactor was 6% which was larger than in Example 7. The average sphericalaberration of the 100 projections was 0.3 λ which was larger (6 times)than in Example 7 and its standard deviation (variation) was 0.01 λwhich was 10 times larger than in Example 7. Since the projectionsgreatly differed from one another in height and were not spherical, theshape of the convergent beam spot was bad with a diameter of 10 μm. Thefocusing distances greatly varied from 2,900 to 3,600 μm. Further, whenthe heat resistance of the board was evaluated in the same manner as inExample 7, the film cracked, peeled off and greatly deformed. Therefore,the focusing distance and spherical aberration could not be evaluated.

Comparative Example 4

0.075 mol of phenyl triethoxysilane, 0.1 mol of dimethyl diethoxysilaneand 0.063 mol of (3,3,3-trifluoropropyl)trimethoxysilane were placed ina beaker and stirred. 0.25 mol of ethanol was added to this solution andstirred, and further an aqueous solution prepared by dissolving 0.1 wt %of formic acid in 1.75 mols (31.5 g) of water was added to this andstirred for 2 hours to prepare a solution. When this solution was usedin place of the solution A in Example 7 to form a board having fineirregularities in the surface in the same manner as in Example 7, thethickness of the most thin region was about 50 μm. As for the heights ofthe projections of this board, when 100 spherical projections selectedat random were measured, the average shrinkage factor was 10% which waslarger than in Example 7. The average spherical aberration of the 100projections was 0.75 λ which was larger (15 times) than in Example 7 andits standard deviation (variation) was 0.15 λ which was 15 times largerthan in Example 7. Since the projections greatly differed from oneanother in height and were not spherical, the shape of the convergentbeam spot was bad with a diameter of 12 μm. The focusing distancesgreatly varied from 3,000 to 3,500 μm. Further, when the heat resistanceof the board was evaluated in the same manner as in Example 7, the filmdid not crack or peel off and the focusing distance and sphericalaberration remained the same as the values before the test.

Comparative Example 5

A board having fine irregularities in the surface was formed in the samemanner as in Example 7 except that the substrate 1 not treated with asilane coupling agent was used in place of the substrate 1 subjected tothe surface treatment 1 in Example 7. The focusing distances of theformed convex lenses (microlenses), and the projection height, sphericalaberration and durability of this board having a film (board having fineirregularities in the surface) were the same as in Example 7. However,the adhesion of the film was 20% in an adhesion test which means thatthe adhesion force of the film was not high. In a chemical resistancetest, 80% of the film peeled off.

Example 8

A board having fine irregularities in the surface was manufactured byforming a film on one side of the substrate 2 subjected to the surfacetreatment 1 using the solution B in accordance with the substratecasting process. A glass mold having 120 2.5 cm-long tub-likedepressions having a substantially semi-circular arc section with acurvature radius of 100 μm arranged close to one another in alongitudinal direction to be coated with the same release film as inExample 7, was used as the mold. After final heating, anorganopolysiloxane film having a thickness of the most thin region ofabout 30 μm and a maximum thickness from the top of the semi-circularportion of 130 μm was formed on the substrate 2 and 120 columnar convexmicrolenses were formed in the surface of the film. The thickness of thecoating of the solution A was about 150 μm and degasification conditionsafter coating, ultraviolet light exposure conditions and final heatingconditions were the same as in Example 7.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. A methyl group,methacryl polymerized segment and Si—O structural segment were containedin the film in amounts of 32.0 wt %, 22.5 wt % and 45.5 wt %,respectively. As for the heights of the columnar projections of thissubstrate, when 20 projections selected at random were measured, theaverage height from the surface of the substrate was 130 μm and itsstandard deviation was 0.11 μm. When the heat resistance of thesubstrate was evaluated, the film did not crack and no change was seenin the appearance, projection height, its standard deviation andprojection pitch of the film. In an adhesion test, the adhesion of thefilm was 100% which proved that the film had high adhesive force. In achemical resistance test, the separation of the film was not observed.

Example 9

A board having fine irregularities in the surface was manufactured byforming a film on one side of the substrate 2 subjected to the surfacetreatment 3 using the solution B in accordance with the substratecasting process. The same mold having a release coat as in Example 8 wasused as the mold. After final heating, an organopolysiloxane film havinga thickness of the most thin region of about 30 μm and a maximumthickness from the top of the semi-circular portion of 130 μm was formedon the substrate 2 and 120 columnar convex microlenses were formed inthe surface of the film. The thickness of the coating of the solution Bwas about 150 μm, degasification was carried out gradually at roomtemperature for 5 minutes after coating, and the final pressure was 5Pa. The film was cured by heating the mold on a hot plate at 150° C. for15 minutes to obtain a molded product. The final heating was carried outat 3 Pa and 250° C. for 60 minutes.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. A methyl group,methacryl polymerized segment and Si—O structural segment were containedin the film in amounts of 32.0 wt %, 22.5 wt % and 45.5 wt %,respectively. As for the heights of the columnar projections of thissubstrate, when 20 projections selected at random were measured, theaverage height from the surface of the substrate was 130 μm and itsstandard deviation was 0.11 μm. When the heat resistance of thissubstrate was evaluated, the film did not crack and no change was seenin the appearance, projection height, its standard deviation andprojection pitch of the film. In an adhesion test, the adhesion of thefilm was 100% which proved that the film had high adhesive force. In achemical resistance test, the separation of the film was not observed.

Example 10

A board having fine irregularities in the surface was manufactured byforming a film on one side of the substrate. 1 subjected to the surfacetreatment 4 using the solution B in accordance with the substratecasting process. The same mold having a release coat as in Example 8 wasused as the mold. After final heating, an organopolysiloxane film havinga thickness of the most thin region of about 30 μm and a maximumthickness from the top of the semi-circular portion of 130 μm was formedon the substrate 2 and 120 columnar convex microlenses were formed inthe surface of the film. The thickness of the coating of the solution Bwas about 150 μm, and degasification conditions after coating,ultraviolet exposure conditions and final heating conditions were thesame as in Example 8.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. A methyl group,methacryl polymerized segment and Si—O structural segment were containedin the film in amounts of 32.0 wt %, 22.5 wt % and 45.5 wt %,respectively. As for the heights of the columnar projections of thissubstrate, when 20 projections selected at random were measured, theaverage height from the surface of the substrate was 130 μm and itsstandard deviation was 0.11 μm. When the heat resistance of thesubstrate was evaluated, the film did not crack and no change was seenin the appearance, projection height, its standard deviation andprojection pitch of the film. In an adhesion test, the adhesion of thefilm was 100% which proved that the film had high adhesive force. In achemical resistance test, 5% of the film peeled off.

Example 11

A 2.5 cm-square silicon reflection type echelon diffraction gratinghaving an average thickness of 2.0 mm (about 1,000 irregularities(parallel linear projections) were formed in the surface of a siliconsubstrate by masking or etching, inclined surfaces on the both sides ofeach mountain portion agreed with the plane (1,1,1) of a siliconcrystal, projection height of 20.15 μm, projection width of 14.3 μm,interval between adjacent gratings (interval between peaks) of about24.7 μm, flat portion at the peak (length of the remaining unetchedportion of about 5.0 μm)) was prepared as the mold. This mold was coatedwith the same release film (three Ti, Pt and Au layers) as in Example 7.A board having fine irregularities in the surface which was a reflectiontype echelon diffraction grating having a thickness of the most thinregion of about 40 μm was formed using the substrate 2 subjected to thesurface treatment 1, the above mold and solution A in accordance withthe mold casting process. The thickness of the coating of the solution Awas about 150 μm, and gasification conditions after coating, ultravioletexposure conditions and final heating conditions were the same as inExample 8.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. As for the heights ofthe projections of this board having fine irregularities in the surface,when 10 linear projections selected at random were measured at 100points at intervals of 9 mm in a longitudinal direction, the averageheight was 0.2 μm and its standard deviation was 0.05 μm. A reflectiontype echelon diffraction grating which was a board having fineirregularities in the surface capable of efficiently and selectivelyblazing 1.55 μm light and 1.30 μm light as diffracted light of 26-thorder and diffracted light of 31-st order, respectively, was thusobtained. The average wave aberration measured by an He-Ne laser (λ=633nm) of this reflection type echelon diffraction grating was 0.05 λ andits standard deviation was 0.001 λ. When the heat resistance of thisboard was evaluated, the film did not crack and no change was seen inthe appearance, projection height, its standard deviation, diffractionpattern and wave aberration of the film from the values before the heatresistance test. In an adhesion test, the adhesion of the film was 100%which proved that the film had high adhesive force. In a chemicalresistance test, the separation of the film was not observed.

Example 12

A 3.0 cm-square resin blazed diffraction grating having a thickness of 5mm (pitch of 1.1 μm, groove depth of 0.8 μm, saw-toothed) was preparedas the mold. The surface of this diffraction grating was plated with Crto a thickness of 80 nm in order to improve the releasability of thesurface when it was used as the mold and a 5 nm-thick Au layer wasformed on the surface of the Cr layer by sputtering. A board having fineirregularities in the surface which was a reflection type blazeddiffraction grating having a thickness of the most thin region of about3 μm was formed using the substrate 2 subjected to the surface treatment1, the above mold and solution C in accordance with the mold castingprocess. The thickness of the coating of the solution C was about 150μm, degasification was carried out gradually at room temperature for 5minutes after coating, and the final pressure was 5 Pa. Exposure toultraviolet radiation was carried out at an intensity of 10 mW/cm² androom temperature for 10 minutes and final heating was carried out at 3Pa and 250° C. for 60 minutes.

The organopolysiloxane cured film formed as described above wastransparent and had a refractive index of 1.48. A methyl group,methacryl polymerized segment and Si—O structural segment were containedin the film in amounts of 36.8 wt %, 9.8 wt % and 53.4 wt %,respectively. The thickness of each projection portion was 3.0 μm, thethickness of each depression portion was 2.2 μm and the refractive indexwas 1.48. As for the heights of the projections of this board havingfine irregularities in the surface, when 10 linear projections selectedat random were measured at 100 points at intervals of 9 mm in alongitudinal direction, the average height was 3.0 μm and its standarddeviation was 0.05 μm. A reflection type blazed diffraction gratingwhich was a board having fine irregularities in the surface capable ofefficiently and selectively blazing the primary diffracted light from1.55 μm light was thus obtained. The average wave aberration measured bya He-Ne laser (λ=633 nm) of this diffraction grating was 0.025 λ and itsstandard deviation was 0.001 λ. When the heat resistance of this boardwas evaluated, the film did not crack and no change was seen in theappearance, projection height, its standard deviation, diffractionpattern and wave aberration of the film from the values before the heatresistance test. In an adhesion test, the adhesion of the film was 100%which proved that the film had high adhesive force. In a chemicalresistance test, the separation of the film was not observed.

Example 13

A board having fine irregularities in the surface which was a reflectiontype echelon diffraction grating having a thickness of the most thinregion of about 40 μm was formed using the same mold having a releasecoat as in Example 11, the substrate 2 subjected to the surfacetreatment 2 and the solution D in accordance with the mold castingprocess. The thickness of the coating of the solution D was about 150μm, and gasification conditions after coating, ultraviolet exposureconditions and final heating conditions were the same as in Example 12.

The organopolysiloxane cured film of the board having fineirregularities in the surface manufactured as described above wastransparent and had a refractive index of 1.46. As for the heights ofthe projections of this board having fine irregularities in the surface,when 10 linear projections selected at random were measured at 100points at intervals of 9 mm in a longitudinal direction, the averageheight was 20.2 μm and its standard deviation was 0.05 μm. A reflectiontype blazed diffraction grating which was a board having fineirregularities in the surface capable of efficiently and selectivelyblazing 1.55 μm light and 1.30 μm light as diffracted light of 26-thorder and diffracted light of 31-st order, respectively, was thusobtained. The average wave aberration measured by a He-Ne laser (λ=633nm) of this reflection type echelon diffraction grating was 0.05 λ andits standard deviation was 0.001 λ. When the heat resistance of thisboard was evaluated, the film did not crack and no change was seen inthe appearance, projection height, its standard deviation, diffractionpattern and wave aberration of the film from the values before the heatresistance test. In an adhesion test, the adhesion of the film was 100%which proved that the film had high adhesive force. In a chemicalresistance test, the separation of the film was not observed.

What is claimed is:
 1. A process for producing an article having a predetermined surface configuration, comprising the steps of: setting a composition comprising a compound which contains a dimethylsiloxane skeleton having at least three recurring units and at least one polymerizable organic group in the molecule between and in contact with the surface of a substrate and the molding surface of a mold in the form of a film, said substrate being an inorganic substrate having a surface coated with a surface treating composition which comprises a silicon compound represented by the following formula (3), as a silane coupling agent: R⁴R⁵ _(k)Si(R⁶)_(3-k)  (3) wherein R⁴ is an organic group having a methacryl group, acryl group, epoxy group, allyl group, mercapto group, amino group, or a vinyl group, R⁵ is an alkyl group, R⁶ is a group or atom having hydrolyzability, and k is 0 or 1, or a hydrolyzate thereof, and a compound represented by the following formula (4): M(R⁷)_(p)  (4) wherein M is silicon, titanium, zirconium or aluminum, R⁷ is a group or atom having hydrolyzability, and p is 4 when M is silicon, titanium or zirconium and 3 when M is aluminum, or a hydrolyzate thereof; applying at least one of heat and ultraviolet radiation to the composition in the form of a film; removing the mold and, as required, heating the film; and forming the article in which the surface of the substrate is covered with a film having a surface configuration which is the inversion of the surface configuration of the mold.
 2. The process of claim 1, wherein the composition further comprises a photopolymerization initiator, at least one of the substrate and the mold is made from a material which can transmit ultraviolet radiation, and the ultraviolet radiation is applied to the composition in the form of a film through the substrate or the mold made from the material which can transmit the ultraviolet radiation.
 3. The process of claim 1, wherein the dimethylsiloxane skeleton of the compound is linear and the polymerizable organic group is located at both terminals of the dimethylsiloxane skeleton.
 4. The process of claim 1, wherein the polymerizable organic group of the compound is at least one group selected from the group consisting of acryloxy group, methacryloxy group, vinyl group and epoxy group.
 5. The process of claim 1, wherein the compound which contains a dimethysiloxane skeleton is represented by the following formula (1):

wherein R¹ and R² are each independently a vinyl group or a group having an acryloxy group, methacryl group or epoxy group, and n is an integer of 3 to
 200. 6. The process of claim 1, wherein the compound which contains a dimethysiloxane skeleton is represented by the following formula (2):

wherein R³ is a vinyl group or a group having an acryloxy group, methacryloxy group or epoxy group, m is an integer of2 to 200, and n is an integer of 1 to 50 when R³ is a group having an epoxy group and an integer of 2 to 50 when R³ is another group, with the proviso that m+n is 3 to
 200. 7. The process of claim 1, wherein the substrate is made from at least one selected from the group consisting of glass, ceramic, metal and resin.
 8. The process of claim 1, wherein the surface treating composition contains the compound represented by the formula (4) or a hydrolyzate thereof in an amount of 5 to 50 parts by weight based on 100 parts by weight of the silane coupling agent represented by the formula (3).
 9. The process of claim 1, wherein the inorganic substrate has a film containing the above silane coupling agent and having a thickness of 5 to 200 nm on the surface.
 10. The process of claim 1, wherein the article having a predetermined surface configuration is a reflection type diffraction grating, transmission type diffraction grating, microlens array or Fresnel lens. 